JP2022184770A - Organic-inorganic composite filler, and dental curable composition containing organic-inorganic composite filler - Google Patents

Abstract

To provide organic-inorganic composite fillers that can reduce polymerization shrinkage, increase the mechanical strength of a hardened body, and further maintain the operability and shape retention of the dental curable composition paste before curing well for a long period of time, when blended in a dental curable composition.SOLUTION: In organic-inorganic composite fillers which are composed of porous organic-inorganic composite particles consisting of a composite of an organic resin component and inorganic particles with an average primary particle size of 10 to 1500 nm and which have a cumulative pore volume of 1 to 500 nm of 0.01 to 0.30 cm3/g, two types of organic-inorganic composite fillers each composed of (1) particles with curved surfaces at least in part and (2) particles that do not have a curved shape are mixed and used, so that the particles of above (1) and (2) co-exist as the porous organic-inorganic composite particles, further in which the content of particles with a particle diameter of 5 μm or less in all constituent particles is set to less than 15 vol%.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a novel organic-inorganic composite filler and a dental curable composition containing the organic-inorganic composite filler.

A dental curable composition is generally a paste-like composition composed mainly of a polymerizable monomer (monomer), a filler, and a polymerization initiator. The amount (ratio) and the like affect the operability of the dental curable composition and the esthetics and mechanical strength of the cured product obtained by curing.

For example, when an inorganic filler having a large particle size is added to a curable dental composition, the mechanical strength of the cured product increases, but the surface lubricity and wear resistance of the cured product decrease, and the natural It becomes difficult to obtain a finished surface of a hardened body with a gloss similar to that of a tooth. On the other hand, when a fine inorganic filler having an average particle size of 1 μm or less is blended, the surface lubricity and abrasion resistance of the cured product can be improved, but the fine inorganic filler has a specific surface area of Since it is large, it greatly increases the viscosity. In addition, when the amount of the inorganic filler is reduced, not only does the amount of shrinkage of the cured product increase due to the polymerization shrinkage of the monomer when the curable dental composition cures, but also the mechanical strength of the cured product increases. , etc.

In order to avoid such a so-called trade-off relationship, the use of an organic-inorganic composite filler has been proposed (see Patent Documents 1 and 2, for example). The organic-inorganic composite filler is a composite filler containing fine inorganic fillers in an organic resin, and by using this, it is possible to maintain excellent surface lubricity and abrasion resistance when using fine inorganic fillers. It is also possible to reduce the polymerization shrinkage rate. If the amount of the organic-inorganic composite filler is too large, the paste will become uneven and the operability of the paste will be deteriorated. ), it is possible to prevent the deterioration of the operability and to obtain a paste-like dental curable composition with excellent operability (see Patent Document 2).

As a method for producing the organic-inorganic composite filler, a paste-like curable composition obtained by kneading fine inorganic fillers and a polymerizable monomer in advance is polymerized to obtain a cured product, and then the cured product is crushed. Common. A dental curable composition containing an organic-inorganic composite filler produced by this method has a problem of low strength as a dental curable composition due to weak interfacial bonding between the matrix and the organic-inorganic composite filler. .

As an organic-inorganic composite filler for solving the above-mentioned problems, a pore volume measured by a mercury porosimetry (here, pores refers to pores having a pore diameter in the range of 1 to 500 nm) is 0.01 to 0.01. An organic-inorganic composite filler having an aggregation gap of 30 cm ³ /g has been proposed (see Patent Document 3). Patent Document 3 discloses that a dental curable composition comprising such a porous organic-inorganic composite filler, a polymerizable monomer, and a polymerization initiator is an organic-inorganic composite filler having cohesion gaps. By using, the polymerizable monomer of the curable composition permeates and cures due to capillary action, an anchor effect occurs, and the organic-inorganic composite filler is highly fitted into the cured body of the curable composition. It is described that it is held by the resultant force and the mechanical strength is improved.

JP-A-2000-80013 International Publication No. 2015/125470 pamphlet International Publication No. 2011/115007 pamphlet

As a result of investigation by the present inventors, the mechanical strength of the dental curable composition containing the organic-inorganic composite filler having coherent interstices obtained by the method of Patent Document 3 is considerably high, and the abrasion resistance and aesthetic properties are improved. It is possible to obtain an excellent dental curable composition. However, the production method described in the Examples, specifically, the inorganic primary particles are aggregated by spray-drying an aqueous suspension in which the inorganic primary particles are dispersed to produce aggregates of the inorganic primary particles, and the resulting inorganic aggregated particles In addition, the paste property and operability of the dental curable composition containing the organic-inorganic composite filler obtained by impregnating the polymerizable monomer containing the polymerization initiator and polymerizing it were examined in detail. As a result, it was found that in the paste state before hardening, stickiness may occur and operability is not good, and when filling class I molar cavities, etc., the ability to maintain the formed occlusal surface shape is low. . In other words, the curable dental composition has room for improvement in terms of paste handleability and shape retention.

Against the above background, the present invention provides an organic-inorganic composite filler to be blended in a dental curable composition, which can increase the mechanical strength of the cured product of the dental curable composition, It is an object of the present invention to provide an organic-inorganic composite filler which has good operability and shape retention in a paste state and can maintain good operability for a long period of time.

The present invention is intended to solve the above problems, and a first form of the present invention comprises an organic resin component (A1) made of a cured product of a polymerizable monomer (a1) and an average primary particle size of 10 to 1500 nm inorganic particles (B1), composed of first porous organic-inorganic composite particles (C1) having curved surfaces at least in part, when measured by a nitrogen adsorption method. A first organic-inorganic composite filler (X1) having a cumulative pore volume of pores of 1 to 500 nm of 0.01 to 0.30 cm ³ /g; and an organic resin comprising a cured polymerizable monomer (a2). Composed of a composite of component (A2) and inorganic particles (B2) having an average primary particle size of 10 to 1500 nm, and composed of second porous organic-inorganic composite particles (C2) having no curved surface shape. and a second organic-inorganic composite filler (X2) having a cumulative pore volume of 0.01 to 0.30 cm ³ /g of pores of 1 to 500 nm measured by a nitrogen adsorption method;
Both the first organic-inorganic composite filler (X1) and the second organic-inorganic composite filler (X2) have an average particle diameter of 5 to 100 μm, and the first porous organic-inorganic composite particles (C1) and the The organic-inorganic composite filler is characterized in that the content of particles having a particle diameter of 5 μm or less in the whole of the second porous organic-inorganic composite particles (C2) is less than 15% by volume.

In the organic-inorganic composite filler of the above form (hereinafter also referred to as "the organic-inorganic composite filler of the present invention"), the total mass of the first organic-inorganic composite filler (X1) and the second organic-inorganic composite filler (X2) It is preferable that the mass ratio of the second organic-inorganic composite filler (X2) to the weight is 10 to 85% by mass.

Further, the average content of the inorganic particles (B1) in the first porous organic-inorganic composite particles (C1) is 75 to 90% by mass, and the inorganic particles in the second porous organic-inorganic composite particles (C2). It is preferable that the average content of (B2) is 80 to 95% by mass.

Furthermore, it is preferable that the inorganic particles (B1) and/or (B2) contain inorganic particles having X-ray contrast properties.

A second form of the present invention is a dental curable composition comprising 100 parts by mass of a polymerizable monomer, 200 to 600 parts by mass of a filler, and an effective amount of a polymerization initiator, wherein 30 parts by mass of the filler % or more of the organic-inorganic composite filler of the present invention.

In the above-described dental curable composition (hereinafter also referred to as "dental curable composition of the present invention"), 30 to 70% by mass of the filler is the organic-inorganic composite filler of the present invention, and the remainder is It is preferable that the main part of the filler is inorganic particles having an average primary particle diameter of 10 to 1500 nm.

When the organic-inorganic composite filler of the present invention is used as a filler for a dental curable composition, similarly to the dental curable composition blended with the porous organic-inorganic composite filler described in Patent Document 3, Not only can the polymerization shrinkage be reduced compared to the case where the inorganic filler is directly blended, but also the surface lubricity and abrasion resistance of the cured product can be improved, and furthermore, The mechanical strength of the cured body can be improved by curing the polymerizable monomer that has permeated into.

In addition, when the organic-inorganic composite filler of the present invention is used, the paste properties of the curable dental composition are not deteriorated, and the paste exhibits good operability with suppressed stickiness even after long-term storage. Not only can the properties be maintained, but it is also possible to improve the shape retention when used as a dental filling material and shaped into a desired shape such as an occlusal surface shape. In addition, since the content of fine particles of 5 μm or less is low, it is possible to suppress the spread of the paste. Furthermore, since a relatively large amount of fine inorganic particles can be added while maintaining good paste properties, polymerization shrinkage can be further reduced.

1 is a scanning electron micrograph of first porous organic-inorganic composite particles (C1) having curved surfaces at least partially, which constitute the first organic-inorganic composite filler (X1) used in the present invention. 2 is a scanning electron micrograph of second porous organic-inorganic composite particles (C2) having no curved surface, which constitute the second organic-inorganic composite filler (X2) used in the present invention.

In the organic-inorganic composite filler disclosed in Patent Document 3, the individual particles constituting the organic-inorganic composite filler basically have the same shape as the inorganic agglomerated particles due to the manufacturing method described above. and is approximately spherical. The inventors of the present invention thought that changing the shape of the organic-inorganic composite filler from a substantially spherical shape to an irregular shape would enable the paste property to be changed, and conducted earnest studies. As a result, when a blocky microporous body composed of a composite of an organic resin component composed of a cured polymerizable monomer and the inorganic primary particles is obtained and then pulverized, the method described in Patent Document 3 can be obtained. The present inventors have found that it is possible to maintain the excellent characteristics of the porous organic-inorganic composite filler while compensating for its shortcomings, and to improve the operability and shape retention of a dental curable composition (paste) containing the same. . Then, based on these findings, "a porous composite made of a composite of an organic resin component (A) made of a cured polymerizable monomer (a) and inorganic particles (B) having an average primary particle diameter of 10 to 1000 nm An organic-inorganic composite filler consisting of an aggregate of organic-inorganic composite particles and having a cumulative pore volume of 0.01 to 0.30 cm ³ /g of pores of 1 to 500 nm measured by a nitrogen adsorption method, The content of the inorganic particles (B) in the porous organic-inorganic composite particles is 80 to 95% by mass, and the individual porous organic-inorganic composite particles constituting the organic-inorganic composite filler have an irregular shape. , an organic-inorganic composite filler characterized by "(hereinafter also referred to as "amorphous microporous organic-inorganic composite filler") and a dental curable composition containing the same (hereinafter referred to as "proposed dental curable composition (also referred to as "thing") has already been proposed (Japanese Patent Application No. 2020-210301).

The inventors of the present invention further studied the effect of the amorphous microporous organic-inorganic composite filler, and found that all the organic-inorganic composite fillers contained in the dental curable composition were It was confirmed that a dry feeling may occur when it is set. Therefore, as a result of further studies to suppress the occurrence of such a phenomenon, (1) the substantially spherical microporous organic-inorganic composite filler and the amorphous microporous organic-inorganic composite filler disclosed in the above-mentioned Patent Document 3 When a mixed filler is used, the dry feeling of the paste is reduced, and the filling rate of the filler that can be blended in the dental curable composition may be improved, and (2) when there are many fine particles It has been found that there is a tendency to cause a dry feeling. The present invention is made based on these findings.

It is not clear why the operability and shape retention of the paste are improved when the amorphous microporous organic-inorganic composite filler is used. It is presumed that the irregular shape preferably has an edge portion, so that the stickiness does not occur and the shape retainability is further improved. Furthermore, regarding the fact that the dry feeling of the paste is suppressed, the content ratio of the inorganic component in the porous organic-inorganic composite particles constituting the organic-inorganic composite filler is high, and the affinity with the matrix monomer in the dental curable composition In addition to the small amount of the organic resin component, when the proportion of fine particles is very low, the contact area with the monomer becomes small, so the absorption of the monomer over time by the porous organic-inorganic composite particles. This is thought to be due to the suppression of Although the organic-inorganic composite filler disclosed in Patent Document 3 includes fragment particles partially broken by impact during handling, most of the fragment particles also have curved surfaces. Since fine particles with a particle size of 5 μm or less are hardly generated unless they are actively crushed, when this is used alone, the paste hardly feels dry, but the above-mentioned effect of improving the paste properties can be obtained. presumably it was not possible.

The organic-inorganic composite filler of the present invention, the method for producing the same, and the dental curable composition of the present invention are described in detail below. In this specification, unless otherwise specified, the notation "x to y" using numerical values x and y means "x or more and y or less". In such notation, when only the numerical value y is given a unit, the unit is also applied to the numerical value x. Moreover, in this specification, the term "(meth)acrylic" means both "acrylic" and "methacrylic". Similarly, the term "(meth)acrylate" means both "acrylate" and "methacrylate", and the term "(meth)acryloyl" means both "acryloyl" and "methacryloyl".

1. The organic-inorganic composite filler of the present invention The organic-inorganic composite filler of the present invention comprises a mixture of the following first organic-inorganic composite filler (X1) and the following second organic-inorganic composite filler (X2). The composite filler (X1) and the second organic-inorganic composite filler (X2) both have an average particle diameter of 5 to 100 μm, and the first porous organic-inorganic composite particles (C1) and the second porous organic It is characterized in that the content of particles having a particle diameter of 5 μm or less in the whole inorganic composite particles (C2) is less than 15% by volume.

First organic-inorganic composite filler (X1): A composite of an organic resin component (A1) made of a cured polymerizable monomer (a1) and inorganic particles (B1) having an average primary particle diameter of 10 to 1500 nm The cumulative pore volume of pores of 1 to 500 nm when measured by a nitrogen adsorption method, which is composed of the first porous organic-inorganic composite particles (C1) having curved surfaces at least in part, is 0.5. 01 to 0.30 cm ³ /g organic-inorganic composite filler.

Second organic-inorganic composite filler (X2): A composite of an organic resin component (A2) composed of a cured polymerizable monomer (a2) and inorganic particles (B2) having an average primary particle diameter of 10 to 1500 nm The cumulative pore volume of pores of 1 to 500 nm when measured by a nitrogen adsorption method, which is composed of the second porous organic-inorganic composite particles (C2) having no curved surface shape, is 0.01 to 0.01. An organic-inorganic composite filler of 30 cm ³ /g.

Here, the “first porous organic-inorganic composite particles (C1) having curved surfaces at least in part” means porous organic-inorganic composite particles, which are organic-inorganic composite fillers obtained using a scanning electron microscope. When observed, whether the particles have a curved shape (a spherical shape, a substantially spherical shape, a donut shape, or a so-called torus shape such as a dimple shape in which a depression is formed on the surface of the particle) in which the main outer surface is composed of curved surfaces, Alternatively, it means that the particles with these shapes are fragment particles broken so that the curved shape remains on at least a part of the outer surface (see FIG. 1). Spherical or substantially spherical particles constituting the organic-inorganic composite filler described in Patent Literature 3 or fragment particles thereof correspond to this. In addition, the “second porous organic-inorganic composite particles (C2) having no curved surface shape” are porous organic-inorganic composite particles that do not correspond to the first porous organic-inorganic composite particles (C1). is a so-called amorphous particle whose outer surface is basically composed of a fractured surface, preferably an amorphous particle having an edge portion (see FIG. 2), and the irregular microporous Particles constituting the organic-inorganic composite filler correspond to this.

These first porous organic-inorganic composite particles (C1) and second porous organic-inorganic composite particles (C2) are both organic resin components (A1, A2 ) and inorganic particles (B1, B2) having an average primary particle diameter of 10 to 1500 nm. The polymerizable monomer and the inorganic particles will be described in detail when the method for producing each filler is explained, but there is no particular difference between the two particles. However, the types of the polymerizable monomers (a1) and (a2) that are raw materials for the organic resins (A1) and (A2) may be different from each other. The types of inorganic particles (B1) and (B2) having an average primary particle size of 10 to 1500 nm may also be different from each other, and the average primary particle size may also be different from each other as long as it is within the above range.

The average particle size of the first porous organic-inorganic composite particles (C1) and the second porous organic-inorganic composite particles (C2) does not reduce the filling rate of the filler that can be blended in the dental curable composition. Both should be 5 to 100 μm, more preferably 10 to 100 μm, and most preferably 10 to 70 μm, because good paste properties can be obtained more reliably. If the average particle size exceeds 100 μm, the fluidity of the curable dental composition tends to decrease, and the smoothness in the paste state tends to decrease. On the other hand, if the average particle size is less than 5 μm, the filling rate of the filler that can be blended in the dental curable composition tends to decrease, resulting in a decrease in the mechanical strength of the cured product and the curable dental composition. The tackiness of the object increases, and the operability tends to deteriorate. In particular, when the proportion of fine particles with a particle diameter of 5 μm or less is high, the paste tends to be uneven. Therefore, the proportion of fine particles having a particle diameter of 5 μm or less in the entirety of the first porous organic-inorganic composite particles (C1) and the second porous organic-inorganic composite particles (C2) is less than 15% on a volume basis. There is a need. The proportion of fine particles having a particle diameter of 5 μm or less is preferably less than 10% by volume.

The average particle size of the organic-inorganic composite filler means the median size determined based on the particle size distribution by laser diffraction-scattering method. Specifically, it means the median diameter obtained based on the particle size distribution obtained by laser diffraction-scattering method for a sample prepared by uniformly dispersing 0.1 g of the organic-inorganic composite filler in 10 mL of ethanol.

In addition, from the viewpoint of the effect of reducing polymerization shrinkage, wear resistance, and aesthetics, the inorganic particles (B1) and (B2) in the first porous organic-inorganic composite particles (C1) and the second porous organic-inorganic composite particles (C2) is preferably 75 to 95% by mass. In the first porous organic-inorganic composite particles (C1), the average content of the inorganic particles (B1) is preferably 75 to 90% by mass, particularly 77 to 88% by mass, for manufacturing reasons. In addition, in the second porous organic-inorganic composite particles (C2), particles having an average particle diameter of less than 5 μm are less likely to occur due to crushing during production, and fine particles having a particle diameter of 5 μm or less are removed by classification. The average content of the inorganic particles (B2) in the second porous organic-inorganic composite particles (C2) is , 80 to 95% by weight, particularly preferably 82 to 93% by weight.

The average content of the inorganic particles can be controlled by the amount ratio of the polymerizable monomer and the inorganic particles used during production, but the organic-inorganic composite filler is burned to cure the polymerizable monomer It can also be confirmed by measuring the weight after incinerating and removing the organic resin component of the body.

In the organic-inorganic composite filler of the present invention, the cumulative pore volume of pores of 1 to 500 nm when measured by the nitrogen adsorption method of the first organic-inorganic composite filler (X1) and the second organic-inorganic composite filler (X2) below is It should be between 0.01 and 0.30 cm ³ /g. However, within this range, the accumulated pore volumes of the pores of 1 to 500 nm may be different from each other.

Since the first organic-inorganic composite filler (X1) and the following second organic-inorganic composite filler (X2) have such cumulative pore volumes, the organic-inorganic composite filler of the present invention is blended into the dental curing agent of the present invention. In the case of a curable composition for dental use, the polymerizable monomer (monomer) component of the curable dental composition is the first porous organic-inorganic composite particles (C1) and the second porous organic-inorganic composite particles (C2) The strength of the cured body can be increased by the anchor effect of penetrating into the pores and curing. From the viewpoint of such effects, the cumulative pore volumes of the first organic-inorganic composite filler (X1) and the second organic-inorganic composite filler (X2) are respectively 0.01 to 0.20 cm ³ /g, particularly 0 It is preferably between 0.03 and 0.15 cm ³ /g.

In Patent Document 3, the total pore volume of pores with a pore diameter of 1 to 500 nm is measured by the mercury intrusion method, but the pore volume of pores with a pore diameter in the same range can also be measured by the nitrogen adsorption method. In addition, according to the studies of the present inventors, the pores with a pore diameter of 1 to 500 nm in the (X2) filler have an extremely sharp pore distribution with a pore diameter peak near 50 nm, and are difficult to measure by the mercury porosimetry. It was confirmed that there were substantially no pores with a pore diameter of less than 1 nm and pores with a pore diameter of more than 500 nm, which is difficult to measure by the nitrogen adsorption method. Therefore, in the present invention, the pore size distribution is calculated by the BJH method from the isothermal adsorption curve by nitrogen adsorption, which is measured by the nitrogen adsorption method, which does not require the use of mercury that requires careful handling. The pore volume obtained by

The average pore diameter of pores possessed by the first organic-inorganic composite filler (X1) and the second organic-inorganic composite filler (X2) is not particularly limited, but is preferably 3 to 300 nm for both. , 10 to 200 nm. Within this average pore diameter range, a porous organic-inorganic composite filler having the above pore volume can be easily formed. Here, the average pore diameter of the pores of the organic-inorganic composite filler is the pore volume obtained by calculating the pore diameter distribution by the BJH method from the isothermal adsorption curve by nitrogen adsorption, and the specific surface area calculated by the BET method. Means the average pore diameter calculated from.

When only the first organic-inorganic composite filler (X1) is added to the dental curable composition, the effect of reducing polymerization shrinkage and the wear resistance, aesthetics and strength of the cured product are excellent. In the paste state before hardening, stickiness may occur and operability may not be good, and there is a problem that the ability to maintain the occlusal surface shape formed when filling a molar class I cavity or the like is low. In the organic-inorganic composite filler of the present invention, by blending the second organic-inorganic composite filler (X2), which is an amorphous microporous organic-inorganic composite filler, such problems related to paste properties are solved. From the viewpoint of high paste property improvement effect, the second organic-inorganic composite filler (X2) in the organic-inorganic composite filler of the present invention is the first organic-inorganic composite filler (X1) and the second organic-inorganic composite filler (X2). The ratio of the mass of the second organic-inorganic composite filler (X2) to the total mass of the above is preferably 5 to 90% by mass, particularly preferably 10 to 85% by mass.

As already explained, the particles constituting the organic-inorganic composite filler described in Patent Document 3 correspond to the first porous organic-inorganic composite particles (C1), and when measured by the nitrogen adsorption method of the organic-inorganic composite filler The cumulative pore volume of pores of 1 to 500 nm in is substantially 0.01 to 0.30 cm ³ /g. Therefore, the organic-inorganic composite filler described in Patent Document 3 corresponds to the first organic-inorganic composite filler (X1), and can be suitably used as the first organic-inorganic composite filler (X1) in the organic-inorganic composite filler of the present invention. . In addition, the particles constituting the amorphous microporous organic-inorganic composite filler proposed by the present inventors in Japanese Patent Application No. 2020-210301 (prior application) correspond to the second organic-inorganic composite particles (C2), and the organic-inorganic composite filler The integrated pore volume of pores of 1 to 500 nm measured by the nitrogen adsorption method of No. 1 is 0.01 to 0.30 cm ³ /g. Therefore, the amorphous microporous organic-inorganic composite filler corresponds to the second organic-inorganic composite filler (X2), and can be suitably used as the second organic-inorganic composite filler (X2) in the organic-inorganic composite filler of the present invention.

Therefore, the method for producing the first organic-inorganic composite filler (X1) and the second organic-inorganic composite filler (X2) will be described below based on the matters disclosed in Patent Document 3 and the matters described in the prior application.

2. Method for producing the first organic-inorganic composite filler (X1) The first organic-inorganic composite filler (X1) is prepared according to the method described in Patent Document 3, "Inorganic particles (B1) having an average primary particle diameter of 10 to 1500 nm. A polymerizable monomer containing 3 to 70 parts by mass of a polymerizable monomer (a1) and an effective amount of a polymerization initiator with respect to 100 parts by mass of an organic solvent. A method comprising a dipping step of dipping in a body solution, an organic solvent removing step of removing the organic solvent from the dipped inorganic aggregated particles, and a curing step of polymerizing and curing the polymerizable monomer impregnated in the inorganic aggregated particles. ” can be suitably manufactured by

Various raw materials used in the above method and details of each step will be described below.

2-1. Polymerizable monomer (monomer)
As the monomer (a1), polymerizable monomers such as radically polymerizable monomers and cationic polymerizable monomers used in conventional dental curable compositions can be used without particular limitation. Among them, commonly used (meth)acrylate polymerizable monomers, specifically acidic group-containing (meth)acrylate polymerizable monomers, hydroxyl group-containing (meth)acrylate polymerizable monomers, these substituents It is preferable to use monofunctional and polyfunctional (meth)acrylate polymerizable monomers having no

Examples of (meth)acrylate polymerizable monomers that can be preferably used include the following. That is, the acidic group-containing (meth)acrylate polymerizable monomers include (meth)acrylic acid, N-(meth)acryloyl-p-aminobenzoic acid, 2-(meth)acryloyloxybenzoic acid, 2-( Meth)acryloyloxyethylphenyl hydrogen phosphate, 2-(meth)acryloyloxyethylphosphonic acid and the like can be mentioned. Further, the hydroxyl group-containing (meth)acrylate polymerizable monomers include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, ) acrylate, 2,2-bis[(3-methacryloyloxy-2-hydroxypropyloxy)phenyl]propane, 2,2-bis[4-(4-methacryloyloxy)-3-hydroxybutoxyphenyl]propane 2,2 -bis[4-(4-methacryloyloxy)-3-hydroxybutoxyphenyl]propane and 2,2-bis[4-(4-methacryloyloxy)-3-hydroxybutoxyphenyl]propane. Furthermore, the above monofunctional and polyfunctional (meth)acrylate polymerizable monomers having no substituents include methyl (meth)acrylate, ethyl (meth)acrylate, triethylene glycol dimethacrylate, tetraethylene glycol. dimethacrylate, neopentyl glycol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, 1,6-bis(methacrylethyloxycarbonylamino)trimethylhexane, and the like.

Among these polymerizable monomers, bifunctional or higher, more preferably bifunctional to tetrafunctional polymerizable monomers are preferred because of high polymerizability and particularly high mechanical strength of the cured product. . Moreover, these polymerizable monomers may be used alone or in combination of different types.

When the organic-inorganic composite filler of the present invention is used as a filler for a dental curable composition, the difference between the refractive index of the cured product of the monomer (a1) and the refractive index of the inorganic particles (B1) is 0. .1 or less is preferred. By selecting such a polymerizable monomer, sufficient transparency can be imparted to the obtained organic-inorganic composite filler.

2-2. Inorganic particles having an average primary particle diameter of 10 to 1500 nm The inorganic particles (B1) having an average primary particle diameter of 10 to 1500 nm may have an average primary particle diameter of 10 to 1500 nm, preferably 10 to 1000 nm. , 40 to 800 nm, particularly preferably 50 to 600 nm. When the average primary particle size of the inorganic particles is less than 10 nm, it becomes difficult to form pores in the organic-inorganic composite particles. On the other hand, when the inorganic particles have an average primary particle size of more than 1500 nm, when they are used in a dental hardening composition, the resulting hardened product has reduced polishability, making it difficult to obtain a hardened product with a smooth surface. In addition, the mechanical properties of the resulting cured product, such as bending strength, tend to decrease.

The shape of the primary particles of the inorganic particles is not particularly limited, and spherical, approximately spherical, or amorphous particles can be used. A spherical or substantially spherical shape is preferable from the viewpoint of being excellent in abrasion resistance and surface lubricity and capable of imparting uniform pores to the organic-inorganic composite particles. Incidentally, the substantially spherical shape means that the average degree of uniformity is 0.6 or more. The average degree of symmetry is preferably 0.7 or more, particularly preferably 0.8 or more. Here, the average primary particle diameter of the inorganic particles can be measured using an image analysis software that can measure at least the area of the particles, the maximum length of the particles, and the minimum width of the particles using a scanning or transmission electron microscope. By image analysis performed in the above, for each of 30 or more n inorganic primary particles randomly selected, the primary particle diameter (equivalent circle diameter) X is obtained, X of the i-th particle is defined as Xi, and these It means the number average particle size determined by the following formula (average particle size calculation formula) based on the value.

Similarly, for each of the n inorganic primary particles, the average degree of uniformity is calculated by determining the number of particles (n), the maximum length of each particle (L), and the diameter of each particle in the direction orthogonal to the major axis. is the minimum width (B), and L and B of the i-th particle are Li and Bi, respectively.

The material of the inorganic particles is not particularly limited, and those used as fillers in conventional dental hardening compositions can be used without particular limitation. Specifically, inorganic oxides such as amorphous silica, silica-zirconia, silica-titania, silica-titania-barium oxide, silica-titania-zirconia, quartz, alumina, titania, zirconia, and glass can be used. Moreover, these inorganic oxide particles are preferably sintered at a high temperature in order to make them dense. Then, in order to improve the densification effect by high-temperature sintering, a small amount of an oxide of a Group I metal of the periodic table such as sodium may be contained. In addition, if necessary, cation-eluting inorganic fillers known as dental inorganic fillers such as silicate glass and fluoroaluminosilicate glass, and metal fluorides such as ytterbium trifluoride may be blended. .

Among these inorganic oxide particles, silica-based composite oxide particles are easy to adjust the refractive index and have a large amount of silanol groups on the surface, so that surface modification with a silane coupling agent etc. is easy. is particularly preferred. Silica-zirconia, silica-titania, and silica-titania-barium oxide are also suitable because of their strong X-ray imaging properties. Furthermore, silica-zirconia is most preferable because it gives a hardened body with more excellent wear resistance.

The inorganic particles (B1) can be suitably produced by, for example, a wet method, a dry method, a sol-gel method, or the like. Among them, sol-gel is advantageous for industrial production of fine particles having a spherical shape and excellent monodispersity, and it is easy to adjust the refractive index and impart X-ray contrast properties. It is preferably manufactured by the method. Methods for producing spherical composite oxide inorganic particles by a sol-gel method are disclosed, for example, in JP-A-58-110414, JP-A-58-151321, JP-A-58-156524, JP-A-58- 156526 and the like.

2-3. Immersion step In the immersion step, the inorganic aggregated particles formed by aggregating the primary particles of the inorganic particles (B1) are added to 100 parts by mass of the organic solvent, and 3 to 70 parts by mass of the monomer (a1) and an effective amount of polymerization start. It is immersed in a polymerizable monomer solution containing an agent. Additives such as UV absorbers, pigments, dyes, polymerization inhibitors and fluorescent agents may be added to the polymerizable monomer solution in order to impart various functions to the organic-inorganic composite filler.

The inorganic aggregated particles can be obtained by granulation by spray drying. Here, in the spray drying method, a slurry obtained by dispersing inorganic primary particles in a volatile liquid medium such as water is prepared into fine atomized droplets using, for example, high-speed airflow, and the atomized droplets are formed. It refers to a method of making inorganic aggregated particles by contacting with a high-temperature gas to volatilize a liquid medium and collect a large number of inorganic primary particles dispersed in droplets into substantially one aggregated particle. The particle size and particle size distribution of the aggregated particles are controlled depending on the spray form and spray conditions. The concentration of the inorganic particles in the slurry is not limited as long as it can be atomized by a high-speed air current or a disk-shaped rotating body, but is generally 5 to 50% by mass. Further, the rotation speed of the disk-shaped rotor is generally 1000 to 50000 rpm. If the sprayed slurry is immediately dried with high-temperature air or an inert gas, inorganic agglomerated particles having a uniform particle size can be obtained. The temperature of the gas used for drying is generally 60-300°C. A small amount of the solvent used for preparing the slurry may remain in the inorganic aggregated particles obtained by the spray drying. For this reason, it is preferable to vacuum-dry the obtained inorganic aggregated particles after spray-drying.

The inorganic aggregated particles thus obtained are then mixed with 3 to 70 parts by mass, preferably 10 to 50 parts by mass of a polymerizable monomer and an effective amount of a polymerization initiator with respect to 100 parts by mass of an organic solvent. It is immersed in a polymerizable monomer solution containing. As a result, the polymerizable monomer solution penetrates into the interior of the inorganic aggregated particles due to capillary action through the aggregation gaps of the inorganic aggregated particles. In this case, since the polymerizable monomer is diluted with the organic solvent, the penetration of liquid due to capillary action is high. As a result, the polymerizable monomer solution is filled up to the deep part of the aggregation gaps. In order to improve the wettability with respect to the polymerizable monomer, the inorganic aggregated particles or the inorganic particles (B1) are preferably surface-treated with a hydrophobizing agent such as a silane coupling agent.

The polymerization initiator to be contained in the polymerizable monomer solution may be a photopolymerization initiator, a chemical polymerization initiator, or a thermal polymerization initiator, but there are no restrictions on the working environment such as under light shielding or red light. A thermal polymerization initiator is more preferable because it can be used for Peroxides, azo compounds, boron compounds, sulfinates, etc. can be used as thermal polymerization initiators. Azobisisobutyronitrile has high operational safety and little effect of coloring on organic-inorganic composite fillers. Azo compounds such as are preferably used. The amount of the polymerization initiator to be blended may be an effective amount sufficient to proceed with the polymerization, and is generally 0.01 to 30 parts by mass, preferably 0, per 100 parts by mass of the polymerizable monomer. .1 to 5 parts by mass.

As the organic solvent contained in the polymerizable monomer solution, for example, halogen-based organic solvents, hydrocarbon compounds, alcohol compounds, ether compounds, and ketone compounds can be used, and methanol, ethanol, acetone, dichloromethane, etc. are preferably used. be done.

As a method for impregnating the inorganic aggregated particles with the polymerizable monomer solution, a method of immersing the inorganic aggregated particles in the polymerizable monomer solution is exemplified. Immersion is usually preferably carried out at normal temperature and normal pressure. The mixing ratio of the inorganic aggregated particles and the polymerizable monomer solution is preferably 30 to 500 parts by mass, more preferably 50 to 200 parts by mass, of the polymerizable monomer solution per 100 parts by mass of the inorganic aggregated particles. After mixing, when the mixture is allowed to stand still, it is preferably allowed to stand for 30 minutes or longer, and more preferably for 1 hour or longer. The mixture may be stirred by shaking, stirred by centrifugation, pressurized, depressurized, or heated in order to promote the infiltration of the polymerizable monomer solution into the interstices of aggregation.

2-4. Organic Solvent Removal Step and Curing Step In the organic solvent removal step, the organic solvent is removed from the polymerizable monomer solution filled in the aggregation gaps. In removing the organic solvent, substantially the entire amount (usually 95% by mass or more) of the organic solvent that has penetrated into the aggregation gaps of the inorganic aggregated particles is removed by heating system drying, vacuum drying, vacuum freeze drying, or the like. Visually, the removal should be carried out until there are no coagulates sticking together and a powder in a fluid state is obtained.

After removing the organic solvent, polymerization curing is performed according to the polymerization initiator used. In the case of thermal polymerization, the polymerization temperature varies depending on the polymerization initiator used, so an optimum temperature may be selected as appropriate. Generally, the polymerization temperature is 30-170°C, preferably 50-150°C.

3. Method for Producing Second Organic-Inorganic Composite Filler (X2) The second organic-inorganic composite filler (X2) can be suitably produced by a method comprising the following slurrying step, drying step, curing step and pulverizing step.

(1) Slurry process: Inorganic particles (B2) having an average primary particle diameter of 10 to 1500 nm and a polymerizable monomer (a2), the ratio of the mass of the inorganic particles to the total mass of both is 80 to 95 mass. % and mixing in the presence of an organic solvent to obtain a slurry in which the insoluble components are uniformly dispersed in the organic solvent;
(2) Drying step: A step of removing the organic solvent from the slurry to obtain agglomerates comprising a mixture of the polymerizable monomer component (a2) and the inorganic particles (B2);
(3) Curing step: The polymerizable monomer component (a2) contained in the aggregated mass is polymerized and cured to obtain an organic resin component (A2) composed of a cured product of the polymerizable monomer (a2). A step of obtaining a massive microporous body composed of a composite with the inorganic particles (B2);
(4) Pulverization step: A pulverization step of pulverizing the massive microporous body into powder.

In the above method, the same polymerizable monomer (a1) and inorganic particles (B1) can be used as the polymerizable monomer (a2) and the inorganic particles (B2). As an organic solvent, 2-3. The same organic solvent used in the soaking process can be used. Further, in the slurry process, 2-3. It is preferable to blend an effective amount of the same polymerization initiator as used in the immersion step. Furthermore, in order to impart various functions to the organic-inorganic composite filler, additives such as ultraviolet absorbers, pigments, dyes, polymerization inhibitors, and fluorescent agents may be blended.

In the above (1), the surface-treated inorganic particles (B2) and the polymerizable monomer (a2) are combined according to the desired inorganic filler particle content of the organic-inorganic composite filler. The proportion of the inorganic particles (B2) in the total amount is 80 to 95% by mass, preferably 82 to 93% by mass, mixed in the presence of an organic solvent, and added to the organic solvent. A slurry in which an insoluble component is uniformly dispersed is obtained.

When inorganic particles (B2) that have been surface-treated with a silane coupling agent by the spray drying method and dried by heating at a temperature of 120° C. or higher are used as the inorganic particles (B2), approximately spherical aggregated particles are formed. By making a uniform slurry in the presence of an organic solvent after surface treatment and heat drying under the conditions, the aggregated particles are crushed and the individual inorganic particles (B2) are evenly mixed with the polymerizable monomer (a2). It is wetted to the touch so that a homogeneous agglomerate can be obtained after the drying step. The amount of the organic solvent used in the slurrying step may be any amount as long as a uniform slurry can be obtained. It is preferably 20 to 500 parts by weight, particularly preferably 30 to 100 parts by weight, per 100 parts by weight of the total weight of the polymerizable monomer (a2).

Mixing for slurry formation may be carried out in one step or in multiple steps, but since a uniform slurry is easily obtained, the inorganic particles (B2) and the polymerizable monomer component (a2) and mixed so that the ratio of the mass of the inorganic particles to the total mass of both is 80 to 95% by mass, and the polymerizable monomer component (a2) is formed on the surface of the inorganic particles (B2). A first step of obtaining a mixed powder consisting of the adhered wet powder; and a second step of mixing the mixed powder and an organic solvent to obtain a slurry in which an insoluble component is uniformly dispersed in the organic solvent; It is preferable to do it separately.

At this time, mixing in the first step is preferably performed using a mixing device from the viewpoint of uniformity. For example, a rocking mixer or a planetary mixer that mixes with stirring blades can be used. As the mixing method in the second step, shaking and stirring, ultrasonic stirring, or stirring and mixing using a kneader can be suitably employed.

In the drying step (2), the organic solvent is removed from the slurry to obtain an aggregated mass comprising a mixture of the polymerizable monomer component (a2) and the inorganic particles (B2). In this drying step, the individual particles of the inorganic particles (B2) are interconnected with the polymerizable monomer component (a2) as a binder to form aggregates, and pores (open to the outside) between the particles is formed. The removal of the organic solvent is preferably carried out until substantially all of the organic solvent (usually 95% by mass or more) is removed and a visually clumpy solid is obtained. The removal operation of the organic solvent is not particularly limited as long as such removal is possible, but from the viewpoint of desired pore formation, it is performed under a reduced pressure of 0.01 to 50 hectopascals, particularly 0.1 to 10 hectopascals. It is preferable to perform drying under reduced pressure (or vacuum drying).

Polymerization curing in the curing step (3) may be carried out by appropriately selecting a suitable method according to the type of the polymerization initiator to be used. The organic-inorganic composite filler of the present invention can be produced by pulverizing the polymerized and cured product (lump microporous material) obtained by polymerization and curing in the pulverization step (4). Pulverization can be performed using a vibrating ball mill, bead mill, jet mill, or the like. Furthermore, if necessary, it may be classified using a sieve, an air classifier, an elutriation classifier, or the like. As described above, the first porous organic-inorganic composite particles (C1) having a particle diameter of 5 μm or less contained in the first organic-inorganic composite filler (X1) are few, and the particle diameter contained in the inorganic-inorganic composite filler of the present invention is Most of the particles of 5 μm or less are the second porous organic-inorganic composite particles (C2). Therefore, the amount of particles of 5 μm or less contained in the organic-inorganic composite filler of the present invention is reduced according to the content of the first organic-inorganic composite filler (X1), and even if no particular classification is performed, the content can be less than 15% by volume.

4. Dental curable composition of the present invention The dental curable composition of the present invention contains 100 parts by mass of a polymerizable monomer, 200 to 600 parts by mass of a filler, and an effective amount of a polymerization initiator. The composition is characterized in that 30% by mass or more of the filler is the organic-inorganic composite filler of the present invention.

When the filler content is outside the above range, the strength of the cured product is low, and when the organic-inorganic composite filler of the present invention in the filler is less than the above lower limit, the effect of reducing polymerization shrinkage and the strength are improved. At least one of the effect and the effect of improving paste properties cannot be obtained. From the viewpoint of these effects, it is preferable that the content of the filler is 100 to 800 parts by mass, particularly 200 to 600 parts by mass, based on 100 parts by mass of the polymerizable monomer.

As the polymerizable monomer, those used for the purpose can be used without limitation. Generally, the same polymerizable monomers as those used in producing the organic-inorganic composite filler of the present invention can be used. However, it is not necessary to use exactly the same organic-inorganic composite filler as that actually used in the present invention, and it may be different.

As the polymerization initiator, those used for the purpose can be used without limitation. In general, a photopolymerization method is often used as a means for curing (polymerizing) a curable dental composition because of its simplicity of operation during use. For the above reasons, it is preferable to use a photopolymerization initiator as the polymerization initiator in the curable dental composition of the present invention as well. Preferred photopolymerization initiators include, for example, benzoin alkyl ethers, benzyl ketals, benzophenones, α-diketones, thioxanthone compounds, bisacylphosphine oxides and the like. A reducing agent is often added to the photopolymerization initiator. Examples of reducing agents include aromatic amines, aliphatic amines, aldehydes, and sulfur-containing compounds. Furthermore, trihalomethyltriazine compounds, aryliodonium salts and the like can be added as necessary. The polymerization initiator is generally blended in the range of 0.01 to 10 parts by mass with respect to 100 parts by mass of the polymerizable monomer.

The filler may contain other fillers such as inorganic fillers and other organic-inorganic composite fillers as long as the content of the organic-inorganic composite filler of the present invention is 30% by mass or more. From the viewpoint of the aesthetics of the cured product and the effect of reducing the polymerization shrinkage rate, it is preferable that the main part of the filler is inorganic particles having an average primary particle diameter of 10 to 1500 nm. As the inorganic particles, the same particles as in (B1) and (B2) can be used. However, the organic-inorganic composite filler of the present invention to be used does not have to be exactly the same as that actually used, and may be different. The main part means that the other filler accounts for 90% by mass or more, preferably 95% by mass or more. Fine fillers and the like can also be included.

Further, known additives can be added to the dental curable composition of the present invention as long as they do not significantly impair its effects. Such additives include polymerization inhibitors, pigments, ultraviolet absorbers, fluorescent agents, and the like.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples.

1. Raw Materials and Their Abbreviations/Abbreviations Various raw materials and their abbreviations used in Examples and Comparative Examples are shown below.

(1) Polymerizable monomer 3G: triethylene glycol dimethacrylate GMA: 2,2-bis[(3-methacryloyloxy-2-hydroxypropyloxy)phenyl]propane UDMA: 1,6-bis(methacryl Ethyloxycarbonylamino)-2,2-4-trimethylhexane HD: 1,6-hexanediol dimethacrylate.

(2) Inorganic particles (inorganic filler)
・F-1: Spherical silica-zirconia particles produced by a sol-gel method (average particle diameter of primary particles: 200 nm, average uniformity of primary particles: 0.95)
・F-2: Spherical silica-zirconia particles produced by a sol-gel method (average particle size of primary particles: 400 nm, average uniformity of primary particles: 0.95)
・F-3: Silica-titania particles produced by a sol-gel method (average particle size of primary particles: 70 nm, average uniformity of primary particles: 0.95)
・F-4: Irregular silica-zirconia particles produced by a sol-gel method (average particle size of primary particles: 1000 nm)
・ F-5: Spherical ytterbium trifluoride particles (average particle size of primary particles: 50 nm)
The average particle size of the primary particles was determined by taking a photograph of the powder at a magnification of 5,000 to 100,000 times with a scanning electron microscope ("XL-30S" manufactured by Philips) and analyzing the image with image analysis software ("IP-1000PC", (trade name; manufactured by Asahi Kasei Engineering Co., Ltd.), the photographed image is processed, and the primary particle diameter (equivalent to a circle Diameter) means the number average particle diameter calculated from the above average particle diameter calculation formula based on X. Further, the average degree of uniformity means a value obtained by calculating the maximum diameter of each of the above particles from the above-mentioned average degree of uniformity calculation formula based on the major diameter (L) and the minor diameter (B).

(3) Polymerization initiator AIBN: azobisisobutyronitrile CQ: camphorquinone DMBE: ethyl N,N-dimethyl-p-benzoate.

2. Evaluation method of organic-inorganic composite filler (1) Measurement method of average particle size (particle size) of organic-inorganic composite filler 0.1 g of organic-inorganic composite filler was dispersed in 10 ml of ethanol and irradiated with ultrasonic waves for 20 minutes. Using a particle size distribution meter (“LS230”, manufactured by Beckman Coulter) using a laser diffraction-scattering method and applying an optical model “Fraunhofer”, the median diameter of volume statistics was obtained.

In addition, when measuring the average particle diameter (particle size), the volume-based abundance ratio (fine particle abundance ratio) in the range of 0.04 μm to 5.0 μm was determined from the obtained particle size distribution.

(2) Method for measuring pore volume and average pore diameter of organic-inorganic composite filler Put 0.1 g of organic-inorganic composite filler in a sample cell, and use a pretreatment device (“Vacu Prep 061” manufactured by Shimadzu Corporation). , and 120° C. for 3 hours by evacuation. After that, using nitrogen as the adsorption gas and liquid nitrogen as the refrigerant, a nitrogen adsorption isotherm is determined by a gas adsorption pore size distribution measuring device ("Tristar II3020" manufactured by Shimadzu Corporation), and the pore diameter is determined by the BJH method. An integrated pore volume was determined in the range of 1 to 500 nm. Also, the average pore diameter was calculated from the pore volume and the specific surface area calculated by the BET method.

3. Production Examples of First Organic-Inorganic Composite Filler (X1) (Production Examples 1 to 4)
Production example 1
100 g of inorganic filler F-1 was added to 200 g of water, and a dispersion liquid in which the inorganic filler was dispersed was obtained using a circulation type pulverizer SC mill. Then, γ-methacryloyloxypropyltrimethoxysilane and acetic acid were added to water and stirred to obtain a uniform solution of pH 4. This solution was added to the inorganic particle dispersion and mixed uniformly. After that, while mixing the dispersion liquid, a spray dryer (spray dryer "NL-5", manufactured by Okawara Kakoki Co., Ltd.) is used to make fine particles by colliding with the atomized air at the tip of the nozzle, and the spray pressure is reduced to 0. Drying was carried out by a spray drying method at a pressure of 08 MPa and a drying temperature of 230°C. Thereafter, the spray-dried inorganic powder was vacuum-dried at 120° C. for 18 hours to obtain inorganic aggregated particles.
Then, a polymerizable monomer solution obtained by mixing 12.0 g of GMA and 8.0 g of 3G as polymerizable monomers, 0.08 g of AIBN as a polymerization initiator, and 80 g of ethanol as an organic solvent is added to the inorganic aggregation 80 g of particles were soaked. After sufficiently stirring and confirming that the mixture became a slurry, the mixture was allowed to stand still for 1 hour.

While stirring the above mixture with a rotary evaporator, it was dried for 1 hour under the conditions of a reduced pressure of 10 hectopascals and a heating condition of 40° C. (using a hot water bath) to remove the organic solvent. Removal of the organic solvent gave a free-flowing powder.
While stirring the above powder with a rotary evaporator, it is heated for 2 hours under the conditions of a pressure reduction of 10 hectopascals and a heating condition of 100°C (using an oil bath) to polymerize the polymerizable monomer in the powder. Hardened. The obtained organic-inorganic composite filler had a substantially spherical shape and an average particle diameter of 20 μm. 04 cm ² /g and the average pore size was 48 nm. As shown in FIG. 2, it was confirmed that it corresponds to X1) filler having a curved surface shape.

Production Examples 2 and 4
An organic-inorganic composite was prepared in the same manner as in Production Example 1 except that the type of polymerizable monomer component to be blended in the organic-inorganic composite filler and the blending amount of the inorganic filler and the polymerizable monomer component were changed as shown in Table 1. A filler was obtained, and each physical property was evaluated in the same manner as in Production Example 1. The results are also shown in Table 1.

Production example 3
100 g of inorganic filler F-1 was added to 200 g of water, and a dispersion liquid in which the inorganic filler was dispersed was obtained using a circulating pulverizer SC mill. Then, γ-methacryloyloxypropyltrimethoxysilane and acetic acid were added to water and stirred to obtain a uniform solution of pH 4. This solution was added to the inorganic particle dispersion and mixed uniformly. After that, while mixing the dispersion liquid, it was supplied onto a disk rotating at high speed and dried by a spray drying method. The spray dryer used was a centrifugally atomized spray dryer (spray dryer “TSR-2W”, manufactured by Sakamoto Giken Co., Ltd.) equipped with a rotating disk. The disk rotation speed was 10000 rpm and the spray drying temperature was 200°C. Thereafter, the spray-dried inorganic powder was vacuum-dried at 120° C. for 18 hours to obtain inorganic aggregated particles.
Then, a polymerizable monomer solution obtained by mixing 9.0 g of GMA and 6.0 g of 3G as polymerizable monomers, 0.06 g of AIBN as a polymerization initiator, and 80 g of ethanol as an organic solvent is added to the inorganic aggregation 85 g of particles were soaked. After sufficiently stirring and confirming that the mixture became a slurry, the mixture was allowed to stand still for 1 hour.

While stirring the above mixture with a rotary evaporator, it was dried for 1 hour under the conditions of a reduced pressure of 10 hectopascals and a heating condition of 40° C. (using a hot water bath) to remove the organic solvent. Removal of the organic solvent gave a free-flowing powder.
While stirring the above powder with a rotary evaporator, it is heated for 2 hours under the conditions of a pressure reduction of 10 hectopascals and a heating condition of 100°C (using an oil bath) to polymerize the polymerizable monomer in the powder. Hardened. The obtained organic-inorganic composite filler had a substantially spherical shape and an average particle diameter of 50 μm. 10 cm ² /g, average pore size was 50 nm.

4. Production Examples of the Second Organic-Inorganic Composite Filler (X2) (Production Examples 5 to 13)
Production example 5
Slurry process:
Surface Treatment of Inorganic Particles: 100 g of inorganic filler F-1 was added to 200 g of water, and a dispersion liquid in which the inorganic filler was dispersed was obtained using a circulation type pulverizer SC mill. Then, γ-methacryloyloxypropyltrimethoxysilane and acetic acid were added to water and stirred to obtain a uniform solution of pH 4. This solution was added to the inorganic particle dispersion and mixed uniformly. After that, while mixing the dispersion liquid, it was supplied onto a disk rotating at high speed and dried by a spray drying method. In the spray drying, a spray dryer (spray dryer “TSR-2W”, manufactured by Sakamoto Giken Co., Ltd.) equipped with a rotating disk and atomizing by centrifugal force is used, and the rotation speed of the disk is 10000 rpm. Temperature: 200°C. After that, the spray-dried inorganic powder was vacuum-dried at 80° C. for 18 hours.
First step: 6.0 g of GMA and 4.0 g of 3G as polymerizable monomers, and 0.04 g of AIBN as a polymerization initiator are mixed in advance with 90 g of the obtained powder (inorganic aggregated particles). The mixture of polymerizable monomers prepared above was added and mixed for 30 minutes using a planetary motion stirrer planetary mixer (manufactured by Inoue Seisakusho) at a stirring blade rotation speed of 7 to 10 rpm to obtain a mixed powder.
Second step: 40 g of ethanol as an organic solvent was added to the mixed powder, and the mixture was further mixed to obtain a uniform slurry with high fluidity.

Drying, curing and grinding processes:
The slurry is vacuum dried at 25 ° C. using a vacuum dryer, ethanol is distilled off, and then heated at 100 ° C. for 2 hours using a vacuum dryer to polymerize and cure the polymerizable monomer. to give a cake-like white solid. Next, this cured product was pulverized for 30 minutes with a vibrating ball mill (zirconia ball diameter: 5 mm), and the pulverized product was sieved to remove particles of 100 µm or more.

The resulting crushed organic-inorganic composite filler had an average particle size of 37 μm, and the volume-based proportion of particles of 5 μm or less in the particle size distribution was 13.5%. The cumulative pore volume was 0.15 cm ² /g, and the average pore diameter was 62 nm. Further, when the shape of each particle constituting the obtained organic-inorganic composite filler was confirmed with a scanning electron microscope, as shown in FIG. It was confirmed that it corresponds to the (X2) filler which is a particle of.

Production Examples 6-10, 12 and 14
Production Example 5 An organic-inorganic composite filler was obtained in the same manner as in , and each physical property was measured in the same manner as in Production Example 5 for each. The results are also shown in Table 1.

Production Example 11
GMA was added as a polymerizable monomer to 76 g of F-1 inorganic aggregated particles surface-treated with γ-methacryloyloxypropyltrimethoxysilane obtained in the same manner as in Production Example 5 and 19 g of inorganic filler F-5. 3.0 g, 2.0 g of 3G, and 0.02 g of AIBN as a polymerization initiator are added to a polymerizable monomer mixture prepared by mixing in advance, and a planetary motion stirrer planetary mixer (manufactured by Inoue Seisakusho) is added. The mixture was mixed for 30 minutes at a stirring blade rotation speed of 7 to 10 rpm to obtain a mixed powder.

40 g of ethanol was added as an organic solvent to the mixed powder, and the mixture was further mixed to obtain a uniform slurry with high fluidity.
The slurry is vacuum dried at 25 ° C. using a vacuum dryer, ethanol is distilled off, and then heated at 100 ° C. for 2 hours using a vacuum dryer to polymerize and cure the polymerizable monomer. to give a cake-like white solid.
Next, this cured product was pulverized for 30 minutes with a vibrating ball mill (zirconia ball diameter: 5 mm), and the pulverized product was sieved to remove particles of 100 µm or more. The obtained crushed organic-inorganic composite filler had an average particle size of 35 μm, and the volume-based proportion of particles of 5 μm or less in the particle size distribution was 9.0%. The cumulative pore volume was 0.09 cm ² /g, and the average pore diameter was 35 nm.

Production example 13
The type of inorganic filler to be blended in the organic-inorganic composite filler, the type of polymerizable monomer component, the blending amount of the inorganic filler and polymerizable monomer component, and the slurrying, drying, and curing steps in the manufacturing process are described above. A cake-like white solid was obtained in the same manner as in Production Example 5. Next, this cured product was pulverized for 120 minutes with a vibrating ball mill (zirconia ball diameter: 5 mm), and the pulverized product was passed through a sieve with an opening of 100 μm to remove particles of 100 μm or more. Each physical property of the crushed organic-inorganic composite filler obtained was measured in the same manner as in Production Example 5. As a result, the average particle diameter was 37 μm, the volume-based abundance of particles of 5 μm or less in the particle size distribution was 20.2%, the cumulative pore volume was 0.09 cm ² /g, and the average pore diameter was 37 nm.

5. Production examples of other organic-inorganic composite fillers (comparative production examples)
Comparative Production Example To 75 g of F-1 inorganic aggregated particles surface-treated with the same γ-methacryloyloxypropyltrimethoxysilane as in Production Example 5, 15.0 g of GMA and 10.0 g of 3G were added as polymerizable monomers. A polymerizable monomer mixture prepared by mixing 0.10 g of AIBN as a polymerization initiator in advance was added, and the mixture was stirred using a planetary motion stirrer planetary mixer (manufactured by Inoue Seisakusho) at a stirring blade rotation speed of 7 to 10 rpm. and mixed for 30 minutes to prepare a pasty mixture. After defoaming the paste-like mixture under reduced pressure, it was polymerized and cured at 100° C. for 2 hours. The cured product was pulverized for 30 minutes with a vibrating ball mill (zirconia ball diameter: 5 mm), and the pulverized product was sieved to remove particles of 100 µm or more. The obtained organic-inorganic composite filler had an irregular shape, an average particle diameter of 45 μm, and no pores were confirmed by measurement by a nitrogen adsorption method.

6. Examples and Comparative Examples Examples 1 to 12 and Comparative Examples 1 to 4
Using each of the organic-inorganic composite fillers shown in Table 1, those corresponding to the organic-inorganic composite filler composition of the present invention were prepared as examples, and those not corresponding to the organic-inorganic composite filler composition were prepared as comparative examples.

For the organic-inorganic composite filler compositions used in the examples, the X1 filler and the X2 filler were mixed in advance at the mixing ratio shown in Table 2, and the presence of particles of 5 μm or less in the particle size distribution was determined in the same manner as in Production Example 1. asked for a percentage.

Using these organic-inorganic composite filler compositions, dental curable compositions of each example were prepared as follows. That is, 0.20 parts by mass of CQ and 0.35 parts by mass of DMBE as polymerization initiators were completely dissolved in a polymerizable monomer consisting of 60 parts by mass of GMA and 40 parts by mass of 3G. After that, in a mortar, the resulting solution, inorganic filler F-1, and each organic-inorganic composite filler were mixed at the mixing ratio shown in Table 2 until uniform, defoamed, and each paste-like sample was obtained. A dental curable composition was prepared.

For each dental curable composition obtained, the operability in a paste state, shape retention and bending strength in a cured product were evaluated by the following methods. The results are shown in Table 3.

(1) Evaluation of operability of curable dental composition in paste state The paste properties of the curable dental composition before curing were evaluated based on the following criteria from the viewpoint of operability. Those with low stickiness were rated as ◯, those with particularly low stickiness were rated as ⊚, and those with paste properties that were highly sticky and difficult to handle were rated as x. Furthermore, the evaluation was given as ◯ for those with little dryness, ⊚ for those with particularly little dryness, and × for those with paste properties that were highly dry and difficult to handle. Evaluation was performed immediately after preparation of the dental curable composition and after storage at 37° C. for 6 months.

(2) Evaluation of shape retention of paste The shape retention of the paste of the curable dental composition before hardening was evaluated by the following method. A hard resin tooth reproducing a class I cavity (diameter 4 mm, depth 2 mm) at the center of the occlusal surface of the lower right No. 6 was filled with the curable composition, and the occlusal surface shape was imparted to the filled paste. After that, the hard resin tooth filled with the dental curable composition was allowed to stand in an incubator at 50° C. for 20 minutes, and whether or not the given form was maintained was evaluated. When a slight change was confirmed in the applied form, it was evaluated as ◯, when there was no change at all, and as x when the form could not be maintained. Evaluation was performed immediately after preparation of the dental curable composition and after storage at 37° C. for 6 months.

(3) Evaluation of bending strength The paste of the curable dental composition was filled into a stainless steel mold using a filling device and pressed with polypropylene. ; light output density of 700 mW/cm ² ) was applied from one side for 30 seconds × 3 times. Next, from the opposite side as well, the film was adhered to polypropylene and irradiated with light three times for 30 seconds to obtain a cured product. #1500 water-resistant abrasive paper, the cured body was arranged into a prism shape of 2 x 2 x 25 mm, and this sample piece was mounted on a tester (manufactured by Shimadzu Corporation, Autograph AG5000D), with a distance between fulcrums of 20 mm and a crosshead speed. Three-point bending breaking strength was measured at 1 mm/min. Five test pieces were evaluated, and the average value was taken as the bending strength. Obtain the load-deflection curve.

The bending strength was obtained from the formula: σ _B =(3PS)/(2WB ² ).
The symbols in the above are, respectively, σ _B : bending strength (Pa), P: load when test piece breaks (N), S: distance between fulcrums (m), W: width of test piece (m), B: Represents the thickness (m) of the test piece.

(4) Shrinkage ratio A stainless steel (SUS) plunger with a diameter of less than 3 mm and a height of 4 mm was slightly loosely fitted into a stainless steel (SUS) split mold with a thickness of 7 mm and a through hole with a diameter of 3 mm. to close one opening of the through-hole and adjust the depth of the hole to 3 mm. Next, after the hole was filled with the curable dental composition, the upper end of the hole was pressed with a polypropylene film. Next, a visible light irradiator Power Light (manufactured by Tokuyama Dental Co., Ltd.; light output density 700 mW/cm ² ) was provided below the center of the glass top plate of the glass table. The SUS split mold was placed on the center upper surface of the glass top plate of the glass table with the surface to which the polypropylene film was attached facing downward. Further, a short needle capable of measuring minute movements of the needle was brought into contact with the upper surface of the SUS plunger. In this state, the curable dental composition was polymerized and cured with a visible light irradiator, and the shrinkage rate (%) 3 minutes after the start of irradiation was calculated from the vertical movement distance of the short needle.

As can be seen from the results of Examples 1 to 12, the dental curable composition blended with the organic-inorganic composite filler composition of the present invention exhibits high bending strength in the cured product and is not sticky or dry in the paste state. shows good shape retention. In addition, changes in operability and shape retention due to long-term storage are extremely small. Furthermore, the shrinkage rate during polymerization is extremely small.

As can be seen from the results of Comparative Example 1, the curable dental composition containing only the porous curved organic-inorganic composite filler (X1) as the organic-inorganic composite filler was highly sticky in the paste state and could not be stored for a long period of time. The change in operability and shape retention is large. In addition, the shrinkage rate during polymerization is large.

As can be seen from the results of Comparative Example 2, the dental curable composition containing only the porous amorphous organic-inorganic composite filler (X2) having a high proportion of fine particles as the organic-inorganic composite filler was in a paste state. Although the stickiness is small, the dryness is large and the shrinkage rate at the time of polymerization is large.

As can be seen from the results of Comparative Examples 3 and 4, the dental curable composition containing the crushed organic-inorganic composite filler having no pores (non-porous) is less sticky in the paste state, Although it has a relatively good shape retention property, it becomes a paste that is difficult to use due to large flaking after long-term storage. In addition, the bending strength of the cured body is also low.

Claims (6)

Composed of a composite of an organic resin component (A1) composed of a cured polymerizable monomer (a1) and inorganic particles (B1) having an average primary particle diameter of 10 to 1500 nm, at least a portion of which has a curved surface. The cumulative pore volume of pores of 1 to 500 nm measured by a nitrogen adsorption method, which is composed of the first porous organic-inorganic composite particles (C1), is 0.01 to 0.30 cm ³ /g. a first organic-inorganic composite filler (X1); and a composite of an organic resin component (A2) composed of a cured polymerizable monomer (a2) and inorganic particles (B2) having an average primary particle diameter of 10 to 1500 nm. The cumulative pore volume of pores of 1 to 500 nm when measured by a nitrogen adsorption method, which is composed of the second porous organic-inorganic composite particles (C2) having no curved surface shape, is 0.01 to 0. .30 cm ³ /g of the second organic-inorganic composite filler (X2);
Both the first organic-inorganic composite filler (X1) and the second organic-inorganic composite filler (X2) have an average particle diameter of 5 to 100 μm, and the first porous organic-inorganic composite particles (C1) and the The content of particles having a particle diameter of 5 μm or less in the whole of the second porous organic-inorganic composite particles (C2) is less than 15% by volume.
An organic-inorganic composite filler characterized by: The second organic-inorganic composite filler (X2) is 10 to 85% by mass with respect to the total mass of the first organic-inorganic composite filler (X1) and the second organic-inorganic composite filler (X2), according to claim 1 Organic-inorganic composite filler. The average content of the inorganic particles (B1) in the first porous organic-inorganic composite particles (C1) is 75 to 90% by mass,
3. The organic-inorganic composite filler according to claim 1, wherein the average content of the inorganic particles (B2) in the second porous organic-inorganic composite particles (C2) is 80 to 95% by mass. The organic-inorganic composite filler according to claim 1, wherein the inorganic particles (B1) and/or (B2) contain inorganic particles having X-ray contrast properties. A dental curable composition comprising 100 parts by mass of a polymerizable monomer, 200 to 600 parts by mass of a filler, and an effective amount of a polymerization initiator, wherein the filler accounts for 30% by mass or more of the dental curable composition according to claim 1. A dental curable composition, characterized in that it is an organic-inorganic composite filler. 30 to 70% by mass of the filler is the organic-inorganic composite filler according to claim 1, and the main part of the remaining filler is inorganic particles having an average primary particle diameter of 10 to 1500 nm. dental curable composition.

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